The present application relates to methods for producing polyols and polyurethanes, and more particularly, to producing polyols from lignocellulosic biomass using a solvent containing crude glycerin. The resulting polyols can be used as starting materials for various products and in particular the polyols can be used to produce polyurethanes.
The industrial manufacturing of polyurethane foam and elastomer products relies significantly on fossil fuels and their derivatives as major reactants for the production of polyols. Certain aspects of the present application are directed to methods of manufacturing polyurethanes using materials that are in abundant supply and obtained from renewable resources. By utilizing renewable resources instead of relying on limited supplies of fossil fuels and derivatives, some aspects of the present invention provide methods for manufacturing polyurethane products through an environmentally friendly process that is also characterized by reduced production costs because the raw materials are readily available byproducts or waste products.
The major global consumption of polyurethane products is in the form of foams which come in two types, flexible and rigid, being roughly equal in market size. In 2007, the global consumption of polyurethane (PU) raw materials was above 12 million metric tons; the average annual growth rate is about 5%. Polyurethane products are used in many different ways as summarized in Table 1 below.
TABLE 1Polyurethane products consumption (US Data 2004)Amount of polyurethanePercentageApplicationused (millions of pounds)of totalBuilding & Construction1,45926.80%Transportation1,29823.80%Furniture & Bedding1,12720.70%Appliances2785.10%Packaging2514.60%Textiles, Fibers & Apparel1813.30%Machinery & Foundry1783.30%Electronics751.40%Footwear390.70%Other uses55810.20%Total5,444100.00%
The general polyurethane polymer-forming reaction between an isocyanate as the A-side component and an alcohol or polyol as the B-side component is as follows:

Typical Reaction of Urethane Formation.
One source of crude glycerin is as a byproduct and waste from the transesterification process of biodiesel production. Biodiesel, produced according to ASTM D 6751, is known as a mono-alkyl methyl ester (fatty acid methyl ester, FAME) or methyl ester for short. It can be made from multiple sources (waste vegetable oil, soybean oil, canola oil, sunflower oil, corn oil, flaxseed oil, cottonseed oil, peanut oil, lard, grease, poultry fat, cooking oil, algae etc.). Crude glycerin derived from biodiesel production has very low value because of its impurities. Generally, crude glycerin appears as a brown liquid since it contains glycerin, methanol, sodium hydroxide, moisture, and some fat residues.